diff --git a/main.c b/main.c
index d6a2b7e..2183dfd 100644
--- a/main.c
+++ b/main.c
@@ -5,6 +5,7 @@
 #include "ascii.h"
 #include "timer.h"
 #include "i2c.h"
+#include "pin.h"
 
 #include "stm32f042x6.h"
 #include "hardwareDescription.h"
@@ -54,15 +55,12 @@ void risingEdgeInterruptPinA1()
 }
 #endif
 
-void TIM2_IRQHandler(void)
-{
-	if(TIM2->SR & TIM_SR_UIF) {
-		
-		// clear flag
-		//TIM2->SR &= ~TIM_SR_UIF;
-		TIM2-> SR = 0;
-
-		//pinWrite(pinB3,1);
+void TIM2_IRQHandler(){
+    /* Check what type of event occurred */
+    if (TIM2->SR & TIM_SR_UIF)
+    {
+        /* Clear the interrupt even flag. CPU will only respond to new flags thereafter */
+        TIM2->SR &= ~(TIM_SR_UIF);
 		pinToggle(pinB3);
 	}
 }
@@ -70,6 +68,7 @@ void TIM2_IRQHandler(void)
 
 void LEDtoggleOnTimer2underflow()
 {
+	/*
 	//timerInitCounter(timer_2, 0xFFFF, 0, upCounting);
 	
 	// reset timer 2 periperal
@@ -101,7 +100,7 @@ void LEDtoggleOnTimer2underflow()
 	TIM2->SR = 0;
 
 	//NVIC_SetVector(TIM2_IRQn, (uint32_t)&TIM2_IRQHandler);
-	NVIC_SetPriority(TIM2_IRQn,0);
+	NVIC_SetPriority(TIM2_IRQn,3);
 	NVIC_EnableIRQ(TIM2_IRQn);
 
 	// timer enable	
@@ -111,13 +110,44 @@ void LEDtoggleOnTimer2underflow()
 
 	while(1)
 	{
-		/*
+		if(TIM2->CNT > 0xFFFF) {
+			pinWrite(pinB3,1);
+		} else {
+			pinWrite(pinB3,0);
+		}
+		
 		if(led_on){
 			pinWrite(pinB3,1);
 		} else{
 			pinWrite(pinB3,0);
 		}
-		*/
+		
+	}
+	*/
+	// example based on
+	// https://alsaibie.github.io/me319/prelabsextra/lab4extra/
+	/* Enable Timer 2 peripheral */
+	RCC->APB1ENR |= RCC_APB1ENR_TIM2EN;
+	/* Default APB1 speed is 16MHz. Scale Timer 2 to 20kHz */
+	//TIM2->PSC = (uint32_t)(16E6 / 20E3) - 1;
+	TIM2->PSC = (8E6 / 20E3) - 1 ;
+	/* Disable Timer*/
+	TIM2->CR1 = 0;
+	/* Reinitialize counter and update registers */
+	TIM2->EGR = TIM_EGR_UG;
+	/* 1000 Counts at 20kHz => 20Hz IRQ */
+	//TIM2->ARR = 1000 - 1;
+	TIM2->ARR = 10000-1;
+	/* Enable hardware interrupts */
+	TIM2->DIER |= TIM_DIER_UIE;
+	/* Start Timer */
+	TIM2->CR1 |= TIM_CR1_CEN;
+	
+	NVIC_SetPriority(TIM2_IRQn, 2);
+	NVIC_EnableIRQ(TIM2_IRQn);
+	
+	while(1)
+	{
 	}
 }